Leaking pipe thread connections

bob young

& lampwick on the threads. problem solved

Charles_8

I'd previously posted about the first gallon or two of hot water being way too hot (from my storage tank heated by the coil). I thought it was thermosiphoning but with more thought, realized that when hot water was drawn, the very hot water in the coil was backing up through the circulator and mixing with the correctly-heated water from the tank. Anyway, this weekend I installed a check valve (swinging-flap) in the line between the circulator and the coil, and now the water temp is constant

However - the only choice at the big-box store was a pipe-threaded check valve. So I got two copper sweat ends, wrapped with Teflon tape and wrench-tight, and screwed them into the valve. Then I soldered the ends to the copper tubing and used a coupling to reconnect to the existing line. Naturally I had a pinhole leak at the coupling, so had to redo that end of the line (and while I had the fitting unscrewed, I used Teflon dope instead of tape). That end doesn't leak...wish I'd done both because:

There was a very small leak (1/4" deep in a 6" diameter pitcher overnight) from the other threaded end where it screws into the valve! I didn't think the temp of the valve body would get high enough during soldering to melt the Teflon, and the protruding tape isn't discolored or melted.

So my question is, what's the best way to prevent this?

1) order a sweat-ends check valve and eliminate the threads entirely (my first choice);

2) sweat one end, screw the valve onto it, then install the other end (the swinging valve may not end up vertical when the threads are tight?);

3) sweat the fittings first with tubing stubs, then solder the stubs to couplings (this will still transfer heat to the thread/tape);

4) a union on each end?

Any tips appreciated.

-Charles

radioconnection_2

unions

Unions are the best way. If you solder after doping and tightening the male adapters, they will leak.

Larry Weingarten

another fix

Also available are brass couplings that are male thread on one end and compression (for copper) on the other. I've seen them up to 3/4". Good for wet places ;~)

Yours, Larry

Unknown

All good advice

from the pros above . I'll throw another out there - heat up the copper adapters first , and while they're still hot tighten them some more before you solder them . You'll find the adapters somewhat loose after you hit them with heat ( I've found out the hard way too many times ) .